Solar hot water collection systems are well known in the prior art. A basic version of collecting heat from the sun is by means of water filled tubes, of a black color to absorb maximum heat from the sun, placed on a random shaped surface exposed to the sun.
Flat plate solar hot water panels are manufactured by integrating a tube type system filled with a heat transfer fluid into a metal absorption panel. Usually this metal panel is flat, black in color and placed in such a manner as to provide the largest surface area to the direct exposure of sunlight—capturing the sun's energy and transferring a portion of the thermal energy provided into usable heat. The flat metal plate is used to capture the thermal energy and the fluid circulating in the pipes embedded into the metal absorption panel transfers the captured heat into the hot water storage tank for end use.
Evacuated tube solar hot water panels operate by heating collection tubes carrying a heat transfer liquid. The collector tubes are located inside a glass tube, where air is removed from the glass tube. Multiple collection tubes are arranged in parallel along a plane surface to form what is basically again a planar collection surface. The sunlight passes through the outer glass tube and heats the collector tubes contained within it. To increase efficiency, usually the tubes are covered with a light-modulating coating.
Typically the collector tubes contain a liquid that vaporizes as it is heated. The vapor rises to a heat-transfer system positioned outside the collector tube in a pipe through which a second heat transfer liquid is pumped. This liquid is connected to the heat storage device in the building. In general, evacuated tube collectors heat to higher temperatures.
Fundamentally, these systems are operating by orienting a pipe or vessel containing a heat transfer fluid to extract as much heat as possible from the sun rays and transfer this heat gain into a usable commodity. The planar systems are oriented in a location that is selected according to the latitude and longitude of the installation location to maximize exposure to the sun.
The prior art planar systems use only one plane of absorption means to extract heat from the sun rays. As the sun moves through the day, the angle of the sun's rays striking the planar collector moves from a shallow inefficient angle in the morning, to a more efficient direct angle at mid-day, and back to the shallow angle in the evening. Furthermore the location of the sun changes through the seasons—seasonal adjustment of the orientation of the planar collector is often suggested or required. A fixed planar absorption plate can thus extract only a fraction of the available energy.